Frost Resistance in Flax. 5 



VARIETAL DIFFERENCES IN FROST RESISTANCE. 



With some selections most of the plants that survived the frost 

 appeared normal except for the purple band and slight constriction, 

 and in other selections the injury to the hypocotyls was much more 

 pronounced. The different kinds of flax varied consistently in the 

 degree of injury from frost. "Wliite Blossom Dutch was usually in- 

 jured so that the entire hypocotyl of every plant was withered, 

 whereas hypocotyl injury could scarcely be detected in Saginaw or 

 Blue Blossom Dutch. 



The percentages of plants that survived the frosts were used as 

 a basis to determine the relative resistance of the flax varieties. 

 Where hj^pocotyl injury, such as purple discoloration or constriction, 

 was noticeable, those plants were not included in the counts but 

 considered eliminated by the frost, for death would as a rule result. 

 The first two frost tests were seeded out of doors in October, 1921. 

 They were both protected by heavy snowfall during the latter half 

 of November and were exposed to freezing temperatures in the first 

 week of December. The flax seeded on October 8 had formed first 

 and second leaves and was more resistant than that planted October 

 20, which was still in the cotyledon stage when injured by frost. All 

 of the imported seeds were of low germinating quality and were 

 eliminated in the first test. Seeds of low germinating power are not 

 resistant to frost, and it is not advisable to use seed of this kind, 

 even though allowance be made for the low germinating power by 

 using an extra heavy rate of seeding. 



Table 2. — Coynparison of frost resistance and icilt resistance in flax varieties. 



[Unless otherwise indicated, the flax varieties in this table are all tall fiber-flax selections developed by th< 

 Office of Fiber Investigations. All seeds used were from the 1921 crop at East Lansing, Alich.] 





Comparative resistance (per cent). 



Varieties planted. 



Stands that survived frost injury on the 

 dates observed. 



Resist- 

 ance to 





Dec. 8. 



Feb. 27. Mar. 18. 



Average. 



wilt. 



No. 21003 



12.5 

 12.6 



12.5 

 12.5 

 12.5 

 8.6 

 7.6 

 9.0 

 4.1 

 9.3 



23.5 

 9.47 



9.23 



5.50 

 7.55 



5.68 



14.04 

 9.87 



9.14 

 8.44 

 8.38 

 6.88 

 6.87 

 5.58 

 5.52 

 5.13 

 3.97 

 2.31 

 2.01 

 1.41 

 1.09 



170 



Blue Blossom Dutch (commercial fiber flax) 



NDR No. 114 (wilt-resistant seed flax, N. Dak. Agr. 

 College") . . 



25 

 70 



Saginaw 



No. 21014 



M 91-1 (seed flax, Minn. Agr. Expt. Station) 



No. 21010 



No. 21029 



No. 21027 



No. 21023 



No. 21004 



9.18 3.75 

 9.3 3.33 

 7.03 5.00 



11.5 1.50 

 7.16 ' 



12.45 

 6.08 

 7.95 

 1.45 2.15 



83 



80 



84 



85 



39 



17 



62.3 



33 



M 74-1 rsp.ftd flaT, Minn, Agr, T'.xpt,. Station), 



3.34 

 



1.6 

 0.7 



82 



White Blossom Dutch (commercial fiber flax) 



No. 21025 



No. 21012 



6.04 

 2.63 

 1.48 





 



1.09 





 42 

 38 



1 Estimated from seedings naade in 1915 and 1919 on infected soil in Michigan. The rest of the data on 

 wilt resistance is largely taken from the notes of J C. Brinsmade, jr., and W. E. Brentzel, of the Office of 

 Cereal Investigations, on 1920 and 1921 seedings at Mandan and Fargo, N. Dak. 



The White Blossom Dutch flax, which is so severely injured by 

 frost, made a strong contrast in percentage of survivals with resistant 

 types. Out of 300 White Blossom Dutch plants that emerged in the 



